Aircraft jet engines may be manufactured using cobalt containing metals and alloy materials. Such metals and alloy materials allow the aircraft jet engines to operate more efficiently by withstanding high temperatures and resisting oxidation and corrosion. However, such cobalt containing metals can be susceptible to corrosion when they react with organophosphorus compounds such as phosphate esters.
In known aviation hydraulic fluids used in the hydraulic systems of aircraft, phosphate esters are the most commonly used base stocks of which tributyl phosphate, isopropylated triphenyl phosphates, n-butyl diphenyl phosphate, and di-n-butyl phenyl phosphate are widely used components. Phosphate esters are typically used due to their fire resistance properties. For example, a known fire resistant aviation hydraulic fluid is SKYDROL, manufactured by Solutia Inc. of St. Louis Mo. (SKYDROL is a registered trademark of Solutia Inc. of St. Louis, Mo.) However, phosphate esters in such aviation hydraulic fluids are polar and tend to absorb atmospheric moisture readily and build up high concentrations of water, for example, 0.3% to 1% water, or more. This can result in the formation of alcohols and acids which can adversely affect the force transmission properties of the hydraulic fluid or induce corrosion.
Such organophosphate-based aviation hydraulic fluids may be used in pumps in jet fuel tanks on a jet aircraft having jet engines manufactured using cobalt containing metals. Due to complete immersion of the pumps in the jet fuel tanks, jet fuel contamination by phosphate esters from organophosphate-based aviation hydraulic fluids can occur and subsequent corrosion of the jet engine can result. In order to prevent contamination of the jet fuel and protect the integrity of the jet engine, the jet fuel should be periodically checked to monitor for the presence of any phosphate esters from organophosphate-based aviation hydraulic fluid. While jet engines not manufactured using cobalt containing metals typically require a concentration level of less than one thousand (1000) parts per million (ppm) of such phosphate esters from organophosphate-based aviation hydraulic fluid in the jet fuel tested, jet engines manufactured using cobalt containing metals require a concentration level of less than one (1) ppm of such phosphate esters from organophosphate-based aviation hydraulic fluid in the jet fuel tested.
Techniques are known for testing jet fuel for detection of organophosphorus compounds, such as phosphate esters from organophosphate-based aviation hydraulic fluid. Such known techniques include inductively coupled plasma spectroscopy and known gas chromatography/mass spectrometry methodologies. However, such known techniques are capable of detecting organophosphorus compounds, such as phosphate esters from organophosphate-based aviation hydraulic fluid in jet fuel, at a concentration level of, at best, ten (10) ppm. Such concentration level is not sufficient for the detection requirement of less than one (1) ppm for jet engines manufactured using cobalt containing metals.
Accordingly, there is a need in the art for a method and system for detecting the required small concentration level of organophosphorus compounds, such as phosphate esters in jet fuel, that provides advantages over known methods and systems.